A casing tool

ABSTRACT

The invention concerns a casing tool and a method for connecting casing tubulars using a top drive. The casing tool comprises a top cover that may be connected either releasably or non-releasably to the top drive and an elongated inner body that may be connected releasingly to the top cover. The inner body displays a longitudinally directed through-going channel, preferably with a gasket near one of its longitudinal ends, and comprises a first longitudinal part slideably arranged within the lop cover and a second longitudinal part that may be guided into a casing tubular. One or more radially displaceable clamps is connected to the lower part of the casing tool for engaging the inside wall of the casing tubular. The radial displacement of the clamps is achieved by use of radial displacement means.

TECHNICAL FIELD

The present invention concerns a casing tool and a method for connecting casing tubulars using a top drive as disclosed in the introductory part of the main claims. More specifically the invention concerns at casing tool that may be releasably fixed to a top drive in a drilling derrick for interconnecting casing tubulars, i.e. casings inserted into drilling holes for hydrocarbon productions.

BACKGROUND AND PRIOR ART

Particularly in oil and gas industry, sections of casing tubulars are being interconnected and inserted into a borehole to achieve the extended length of the borehole lining. To avoid that the interconnected casing string falls into the well while adding a new section, the slips of a spider located on the floor of the drilling platform are often used. The new section or stand of casing is then moved from a rack to the well centre above the spider. The treaded pin of the section of casing tubular to be connected is then located over the threaded box of the casing in the well and the connection is made up by rotation there between. An elevator is then connected to the top of the new section and the whole casing string is lifted slightly to enable the slips of the spider to be released. The whole casing string is then lowered until the top of the section is adjacent the spider whereupon the slips of the spider are re-applied, the elevator disconnected and the process repeated.

It is well known to use a power tong or similar turning means to torque the connection up to a predetermined torque in order to make the connection. These turning means located on the platform, either on rails, or hung from a drilling derrick on a chain, constitute often large and complex machineries which require a considerable amount of space and maintenance.

In the last decades use of top drive has been common in order to perform the interconnection of casing tubulars with sufficient torque strength. This type of operations requires the use of a dedicated tool that may connect to the top drive in one longitudinal end and may engage with the casing tubular at the other end so that the casing tubular can be rotated and lifted/lowered in to/out of the bore hole. An example of connecting tubular sections using a top drive and a corresponding casing tool is disclosed in publication WO 00/05483. This casing tool comprises a plurality of gripping elements that are radially displaceable by hydraulic or pneumatic fluid in order to drivingly engage the tubular section. This again permits a screw connection between the engaged tubular section and a further tubular section with the required torque. Another example of a top drive and a casing tool is found in publication WO 2006/116870 A1 disclosing a casing tool comprising a body assembly and a gripping assembly with a grip surface adapted to move from a retracted position to an engaged position to radially engage a work piece in response to relative axial displacement, the latter being activated by relative rotation within the tool. Further, publication U.S. Pat. No. 8,454,066 B2 discloses a tool for moving rigid spokes arranged in close fitting relation with spike guides on an annular body to allow for radial movements only between a retracted position and an engaged position.

Common for the prior art casing tools of the type described above is the use of either hydraulic or pneumatic fluid or relative rotation within the tool, in order to initiate and complete the process of engaging the tool to the casing tubular. This increases the complexity of the tool, thus releasing important undesired aspects such as higher production cost and higher degree of maintenance.

There is therefore a need to mitigate the disadvantages with the existing systems and to reduce the investments in extra equipment.

It is thus an object of the present invention to present a solution providing an easier and more cost effective activation of the engagement between the tool and the casing tubular, and which also fulfills the requirements of robustness and reliability. Another object of the invention is to provide an engagement mechanism that may be easily released, both in normal operations and in case of certain mechanical malfunctioning.

SUMMARY OF THE INVENTION

The present invention is set forth and characterized in the main claims, while the dependent claims describe other characteristics of the invention.

In particular, the invention concerns a casing tool for connecting casing tubulars using a top drive. The casing tool comprises a top cover that may be connected either releasably or non-releasably to the top drive and an elongated inner body that may be connected releasingly to the top cover. The inner body displays a longitudinally directed through-going channel, preferably with a gasket near one of its longitudinal ends, and comprises a first longitudinal part slideably arranged within the top cover and a second longitudinal part that may be guided into a casing tubular.

The casing tool further comprises a first sleeve arranged concentric and axial displaceable along at least part of the inner body at an axial distance (d) from the top cover, force transferring means for transferring a first external axial force (F1) exerted on the top cover in directed towards the casing tubular at least partly to the first sleeve, at least one clamp connected radially displaceable to the first sleeve for engaging the inside wall of the casing tubular and radial displacement means extending at least partly along the second longitudinal part of the inner body for imparting radial displacement of at least one of the at least one clamp during relative axial displacement of the first sleeve and the inner body. The first external axial force (F1) is preferably exerted after an obstruction of axial displacement of the inner body relative to the casing tubular

In a preferred embodiment the casing tool further comprising a first impact means configured to abut the end of the casing tubing during insertion therein, where an obstruction of the axial displacement of the inner body relative to the casing tubular is ensured by connecting the first impact means to the inner body via the force transferring means, for example when the at least one clamp is in an engaging position. The first impact means may comprise a first impact face situated between the end of the first sleeve facing the top cover and the radial displacement means. Furthermore, the first impact means may be connected by connection means to an outer enclosure radially enclosing at least the end of the first sleeve facing the top cover and the force inducing means.

In another preferred embodiment the force transferring means comprises a second sleeve arranged adjacent to the end of the top cover facing the second longitudinal part and at least one locking means arranged in contact with the axial end of the first sleeve facing the top cover, wherein the force transferring means is configured so that an axial force on the second sleeve activates a mainly casing tubing directed axial displacement of the at least one locking means.

The at least one locking means may comprise at least one pivot arm, where an axial force on the second sleeve causes a mainly outward oriented radial displacement of a first arm of the pivot arm and a mainly casing tubing directed axial force from the second arm of the pivot arm. The second arm may be either in direct or indirect contact with the first sleeve. The second sleeve may further comprise a third sleeve and an annular body connected to an axial end of the third sleeve facing the second longitudinal part and radially abutting a contact face of the first arm of at least one pivot arm, wherein the annular body comprises a radial projection configured to impose the outward directed radial displacement of the first arm during axial displacement of the second sleeve.

Alternatively the at least one locking means may comprise at least one lockable wheel and a lower sleeve, wherein an axial force on the second sleeve causes a release of the at least one lockable wheel and a mainly casing tubing directed axial force from the lower sleeve.

In another preferred embodiment the first sleeve comprises an inner tubing extending at least across the radial displacement means situated on the inner body and a flange or collar connected to the end of the inner tubing facing the top cover. The outer diameter of the flange is larger than the outer diameter of the inner tubing.

In another preferred embodiment the first sleeve displays at least one clamp fitting recess, wherein each recess is configured to allow its corresponding clamp to be displaced in the radial direction only after assembly.

In another preferred embodiment the radial displacement means comprises at least one first tapered face. Furthermore, the at least one of the at least one clamp may comprise at least one second tapered face facing the at least one first tapered face.

In another preferred embodiment the axial end of the top cover facing the second longitudinal part and the axial end of the force transferring means facing the top cover, for example the axial end of the third sleeve, are configured as interacting cam bodies allowing interconnection by rotation. This interconnection may for example be obtained by exerting an external axial force (F) that causes the contact face of the first arm to supersede the radial projection. The interacting cam bodies are advantageously configured to allow a top cover directed axial displacement of the second sleeve when the interacting cam bodies are rotated into the interconnected state and a third external axial force (F3) directed towards the casing tubing is exerted on the top cover. This axial displacement of the second sleeve causes the at least one clamp to release the radial force on the casing tubular set up by the radial displacement during engagement. For example, the displacement may cause the second sleeve to axially disconnect from the at least one pivot arm.

In another preferred embodiment the casing tool further comprising at least one second sleeve connected release mechanism configured to allow a top cover directed axial displacement of the second sleeve. For example, the axial displacement may cause the second sleeve to disconnect from the at least one pivot arm.

The invention also concerns a method using a casing tool in accordance with the above mentioned characteristics. The method comprising the following steps:

-   -   inserting the second longitudinal part of the inner body a         predetermined length into the casing tubular, the length being         set by a first impact means connected to the inner body to         hinder axial displacement of the inner body relative to the         casing tubular and     -   exerting a first casing tubular directed external axial force         (F1) on the top cover causing equally directed axial         displacements of the top cover, the first sleeve and the at         least one clamp,     -   whereby engagement of the casing tool with the casing tubular is         achieved by interaction with the radial displacement means         imparting radial displacement of at least one of the at least         one clamp during said axial displacements.

In other to achieve an additional engagement of the at least one of the at least on clamp the method may further comprise the step:

-   -   releasing the first casing tubular directed external axial force         (F1) on the top cover,     -   exerting a second external axial force (F2) directed opposite to         the first external axial force (F1),

thereby exerting a second external axial force directed tension on the inner body, creating an increase in the relative axial force between the dies and the inner body.

To release the engagement between the casing tool and the casing tubular the following steps may be performed:

-   -   exerting a third external axial force (F3) on the top cover in         direction of the casing tubular causing equally directed axial         displacements,     -   rotating the top cover (either subsequent to the axial         displacement or simultaneously), thereby achieving an         interconnected assembly comprising the top cover, the second         sleeve and the inner body and     -   raising the assembly, causing a top cover directed axial         displacement of the first sleeve and the at least one clamp. The         latter step releases the engagement of the clamp(s) by         interaction with the radial displacement means.

An alternative or additional way of releasing the engagement between the casing tool and the casing tubular is obtained by performing the following step:

-   -   activating at least one second sleeve connected release         mechanism causing a top cover directed axial displacement of the         first sleeve and at least one of the at least one clamp, thereby         releasing the engagement between the casing tool and the casing         tubular through interaction with the radial displacement means.

In the following description, numerous specific details are introduced to provide a thorough understanding of embodiments of the claimed tool and method. One skilled in the relevant art, however, will recognize that these embodiments can be practiced without one or more of the specific details, or with other components, systems, etc. In other instances, well-known structures or operations are not shown, or are not described in detail, to avoid obscuring aspects of the disclosed embodiments.

BRIEF DESCRIPTION OF THE DRAWINGS:

FIG. 1 is a perspective view of the casing tool in accordance with a first embodiment of the invention showing the tool in engaged position,

FIG. 2 is a radial view of the casing tool in accordance with FIG. 1 showing the engaged tool inserted into a casing tubular,

FIG. 3 is a cross sectional view of the casing tool along section A-A of FIG. 2,

FIG. 4 is a radial view of the casing tool in accordance with FIG. 1 with the outer enclosure removed,

FIG. 5 is a cross sectional view of the casing tool along section A-A of FIG. 4,

FIG. 6 is a cross sectional view of the casing tool along section B-B of FIG. 5,

FIG. 7 is a cross sectional view of the casing tool along section C-C of FIG. 5,

FIG. 8 is a cross sectional view of the casing tool in accordance with the invention, showing the end of the tool inserted into the casing tubular,

FIG. 9 is a schematic view showing the principals of converting axial displacement of the dies into radial displacement using tapered faces, wherein FIG. 9(a) is showing the initial engagement due to movement of the die and FIG. 9(b) is showing the additional engagement due to opposite directed tensioning of the inner body,

FIG. 10 is a radial view of the casing tool in accordance with a second embodiment of the invention showing the tool in engaged position,

FIG. 11 is a cross sectional view of the casing tool along section A-A of FIG. 10,

FIG. 12 is a cross sectional view of the casing tool along a section perpendicular to section A-A of FIG. 10 relative to the tools axial axis and

FIG. 13 is a cross section view of the casing tool along a section D-D of FIG. 12.

DETAILED DESCRIPTION OF THE INVENTION

In the following to different embodiments will be disclosed, where both embodiments are based on the following general concept (see for example FIGS. 1-4 and FIGS. 10-12): After inserting a tool 1 into the casing tubular 4,5 the dies 34 on the sleeve 8 engage the inner wall of the lower tubular 6″ by relative (non-rotational) axial displacements of the zigzag patterns 9,9′ in response to a downward directed axial force. The through-going fluid channel 27 and the rubber gasket 7 allows leak free circulation of fluid, rendering fluid flow into the casing tubular 4,5 possible. A subsequent upward directed force strengthens this die engagement. Release of the tool 1 from the casing 4,5 may be performed by a combination of axial force and rotational force.

First Embodiment

FIG. 1 shows one embodiment of the casing tool 1 in a perspective view, while FIGS. 2 and 3 show the same casing tool 1 as in FIG. 1 in a radial view and a cross sectional view along section A-A, respectively, after completing an engaging insertion into a casing tubular 4. In the following the terms upper and lower signify the orientation from and to the casing tubular 4, respectively. Furthermore, the terms outward and inward signify the radial orientation from and to the center of the tool 1, respectively.

With reference to FIGS. 2-7 the particular embodiment of the inventive tool 1 comprises the following main components:

-   -   a top drive part 2 having upper threads in order to connect to a         top drive (not shown),     -   an upper cam body 18 and a lower cam body 16, which bodies 16,18         may be connected and disconnected by simple rotations clockwise         and counterclockwise,     -   lower threads 29 for connecting the top drive part 2 and the         upper cam body 18,     -   an inner tubular 6 comprising an upper tubular 6′ situated         mainly within the top drive part 2 and the upper cam body 18 and         a lower tubular 6″ situated mainly within the casing tubular 4         after complete engagement,     -   a through-going fluid channel 27 extending throughout the entire         length of the inner body 6,     -   an upper impact piece 20 (FIG. 5) connected to the upper tubular         6′ with a lock ring 21 and situated within an annular cavity         formed by the top drive part 2, the upper cam body 18 and the         upper tubular 6′,     -   upper gear teeth 42 (FIG. 6) surrounding the upper tubular 6′         and situated within a cavity formed by the top drive part 2 and         the upper tubular 6′,     -   lower gear teeth 40 (FIG. 7) surrounding the inner tubular 6 and         situated within the lower cam body 16,     -   first cam springs 26 interconnecting the upper and lower cam         bodies 18,16,     -   second cam springs 17 interconnecting the lower cam bodies 16         and the top drive part 2,     -   an annular spring 14,14′ having an outward oriented bulge or         protrusion 14′,     -   a lower impact piece 10 configured to abut the threaded part 5         of the casing tubular 4,5 after insertion,     -   a plurality of pivot arms 12 comprising a long arm 12′, a short         arm 12″ and a pivot point in form of a bolt 13 fixed to the         lower impact piece 10,     -   a sleeve 8 having a flange 11 at its upper end and die recesses         at its lower end,     -   flange springs 25 interconnecting the lower impact piece 10 and         the flange 11,     -   an outer enclosure 3 fixed to the lower impact piece 10 by         screws 24 and surrounding the above mentioned components up to         the top drive part 2,     -   a plurality of dies 34 arranged within the die recesses, where         each die 34 comprises an elastomeric contacting face 19 at its         outward directed radial surface and a die zigzag pattern 9″ at         its inward directed radial surface,     -   tubular zigzag pattern 9′ at the outer wall of the lower tubular         6″, wherein the tubular zigzag pattern 9′ and the die zigzag         pattern 9″ form mirror patterns,     -   rubber gasket 7 arranged below the dies 34 ensuring a fluid         tight seal between the inner wall of the casing tubular 4 and         the lower tubular 6″,     -   tilting levers 35 connected at one end underneath the lower cam         body 16 and at the other end to sheaves 31 via bolt connections         22 and     -   lever screws 23 situated in the sheaves 31.

The top components comprising the top drive part 2, the upper cam body 18, the upper impact piece 20, the lock ring 21 and the upper gear teeth 42 form an assembly called a top cover 100. Further, the mid components comprising lower cam body 16, the lower gear teeth 40, the annular spring 14,14′ and the pivot arms 12 form an assembly called a force transferring means 200.

Initially the tool 1 is lowered into the casing tubular 4,5 until its threaded part 5 abuts the lower impact piece 10, the latter being fixed to the outer enclosure 3. In this starting position the abutting impact piece 10 prevents any downward axial displacement of the inner tubular 6 since the bulge 14′ in the annular spring 14 is located above a contacting face 15 at the end of the long arm 12′ of each pivot arm 12. Further, the end of the short arm 12″ below the pivot point bolt 13 is contacting the upper axial face of the sleeve's 8 flange 11, the latters being arranged concentrically around the inner tubular 6. In the lower half of the sleeve 8 there are arranged die recesses configured to allow only radial displacements of the dies 34 when installed.

In this particular starting position exertion of axial forces on the tool 1 cause corresponding axial displacements of the top drive part 2, the upper impact piece 20 and upper cam body 18. In absence of any rotation the upper cam body 18 will impact the lower cam body 16 in an impact point 32 (FIG. 4), causing an axial force to be exerted also on the lower cam body 16 and the connected annular spring 14. If this latter force is sufficient to overcome the radial spring force exerted by the long arm 12′ on the annular spring 14, the bulge 14′ will move the arm 12′ radially outwards. An axial pressure is thus imparted on the flange 11 by the short arm 12″ causing the sleeve 8 and the attached dies 34 to be axially displaced. Finally, the mirrored zigzag patterns 9,9′ on the dies 34 and the lower tubular 6″ force the dies 34 radially outwards. The desired clamping of the dies 34 onto the inner walls of the inner tubular 6 is thereby achieved. The lower gear teeth 40 ensure that the lower cam body 16 is only displaced in the axial direction. Flange springs 25 may be arranged between the flange 11 and the lower impact piece 10 in order to re-position the sleeve 8 and the flange 11 when the dies 34 are released from the inner tubular 6.

When the contacting surface 15 of the long arm 12′ has passed the center of the bulge 14′ the pivot arms 12 are in a locked position relative to the annular spring 14, the lower cam body 16 and the inner tubular 6. In absence of any rotation the upper cam body 18 and the top drive part 2 may in this pre-tensioning situation be lifted up until impact occurs between the upper cam body 18 and the upper impact piece 20. Exertion of any further upwards directed force would thus be transferred to the lower tubular 6″, causing a larger axial force and thus an additional clamping/tensioning force onto the inner walls of the casing tubular 4 from the dies 34.

It is emphasized that both the initial clamping and the additional clamping are performed without any rotational movements of the tool 1.

Release of the tool 1 from the casing tubular 4 may be achieved by lowering the top drive part 2 and the upper cam body 18 applying a downward directed force, while enforcing a counterclockwise rotation. The latter rotation forms an interconnection between the upper cam body 18 and the lower cam body 16 in contrast to simple impact 32 in absence of rotation. During rotation upper cams 33 with upward directed inclined planes 37 at the lower part of the upper cam body 18 are meshing with corresponding inclined planes 37′ on the upper part of the lower cam body 16, thereby lifting the latter axially upwards. Due to the axial displacement of the now interconnected bodies 16,18 the long pivot arm 12′ looses its grip with the annular spring 14, thus releasing the tool 1 from the casing tubular 4. Upper gear teeth 42 arranged between the top drive part 2 and the upper cam body 18 are configured to mesh with the top drive part 2 when impact 30 exists (or about to take place) between the upper cam body 18 and the upper impact piece 20, i.e. when the top drive part 2 is in its upper position. Further, arrangement of the first cam springs 26 ensure that such an impact 30 prevails in the absence of downward directed axial force (F). The impact piece 20 may be fixed by a locking ring 21. The second cam springs 17 ensure positioning of the top drive part 2 relative to the lower cam body 16.

To be able to release the tool 1 manually, e.g. in case of any loss of rotational freedom between the two cam bodies 16,18, the tool 1 may be arranged with pivoting levers 35 connected underneath the lower cam body 16 in one end and sheaves/plates 31 fixed by bolts 34 at the other end. The plates 31 are fastened to the outer enclosure 3 by screws. To manually release the tool 1 dedicated release or lever screws 23 are inserted so that the pivoting levers 35 pivots around the bolts 34, thereby pressing the lower arm radially inwards and the higher arm axially upwards. The lower cam body 16 experiences thus a corresponding axially displacement, thereby releasing the annular spring 14 from the pre-tensioning long arm 12′. The further mechanisms are identical to the regular release described above.

FIG. 8 shows the axially displaceable sleeve 8, the radially displaceable dies 34, the engagement means 9,9′,9″ and the rubber gasket 7 in further details. The displaced mirror configurations of the zigzag patterns constituting the engagement means is apparent. Due to the sliding action on each or some of the tapered surfaces any axial displacement of either the lower tubular 6″ or the sleeve 8 results in a radial displacement of the dies 34. The same effect is achieved by any relative axial displacement between these two objects 6″.8. The principle of converting axial displacement of the dies 34 into radial displacement using tapered faces is better illustrated in FIGS. 9(a) and 9(b). For the sake of clarity only one tapered surface 9′ on the lower tubular 6″ and only one contacting tapered surface 9″ on the die 34 is shown. When the sleeve 8 is displaced downward (in direction towards the casing tubular), the tapered surface 9″ glides on the mirrored tapered surface 9′, thereby pressing the contacting layer 19 of the die 34 towards the inside wall of the casing tubular 4 (see FIG. 9(a)). Likewise, when the inner tubular 6 experiences a force directed towards the top drive, the tapered surface 9′ glides on the tapered surface 9″, causing an equally directed pressing of the contacting layer 19 towards the inner wall of the casing tubular 4 (see FIG. 9(b)). The situation shown in FIGS. 9(a) and (b) corresponds to the pre-tensioning force and the additional tensioning force described above.

Second Embodiment

FIGS. 10-13 illustrate a second embodiment of the inventive casing tool 1, where FIG. 10 shows the casing tool inserted into a casing as viewed in a radial direction. Further, FIGS. 11 and 12 shows a cross sectional view along a section A-A of FIG. 10 and a cross sectional view along a section perpendicular to section A-A relative to the axial axis, respectively, and FIG. 13 shows a cross sectional view along a section D-D of FIG. 12.

The second embodiment of the inventive tool 1 comprises the following main components:

-   -   a top drive part 2 having threads in order to connect to a top         drive (not shown),     -   an upper cam body 18 and a lower cam body 16, which bodies 16,18         may be connected and disconnected by simple rotations clockwise         and counterclockwise,     -   an inner tubular 6 comprising an upper tubular 6′ situated         mainly within the top drive part 2 and the upper cam body 18 and         a lower tubular 6″ situated mainly within the casing tubular 4         after complete engagement,     -   a through-going fluid channel 27 extending throughout the entire         length of the inner body 6,     -   an upper impact piece 20 connected to the upper tubular 6′ with         a lock ring 21 and situated within an annular cavity formed by         the top drive part 2, the upper cam body 18 and the upper         tubular 6′,     -   upper gear teeth 42 surrounding the upper tubular 6′ and         situated within a cavity formed by the top drive part 2 and the         upper tubular 6′,     -   lower gear teeth 40 (corresponding to FIG. 7 of embodiment 1)         surrounding the inner tubular 6 and situated within the lower         cam body 16,     -   first cam springs 26 interconnecting the upper and lower cam         bodies 18,16,     -   a mid sleeve 51 surrounding the inner tubular 6 and the lower         cam body 16,     -   a lower impact piece 10 fixed by screws 59 to the mid sleeve 51         and configured to abut the threaded part 5 of the casing tubular         4,5 after insertion,     -   second cam springs 17 interconnecting the mid sleeve 51 and the         top drive part 2,     -   releasable wheels 52 situated within recesses along the radial         surface of the lower cam body 16,     -   triangular brackets 53 fixed to the releasable wheels,     -   a lower sleeve 54 surrounding the inner tubular 6 underneath the         lower cam body 16,     -   elongated brackets 55 fixed to the triangular brackets 53 in a         first longitudinal end and to the lower sleeve 54 in a second         longitudinal end,     -   a sleeve 8 having a flange 11 at its upper end and die recesses         at its lower end,     -   an inner tubular flange 56 radially extending from the inner         tubular 6 between the lower cam body 16 and the flange 11,         wherein the inner tubular flange 56 is fixed to the mid sleeve         51 by screws 57,     -   lower sleeve springs 58 interconnecting the flange 11 and the         lower sleeve 54.     -   flange springs 25 interconnecting the lower impact piece 10 and         the flange 11,     -   a plurality of dies 34 arranged within the die recesses, where         each die 34 comprises an elastomeric contacting face 19 at its         outward directed radial surface and a die zigzag pattern 9″ at         its inward directed radial surface,     -   tubular zigzag pattern 9′ at the outer wall of the lower tubular         6″, wherein the tubular zigzag pattern 9′ and the die zigzag         pattern 9″ form mirror patterns,     -   rubber gasket 7 arranged below the dies 34 ensuring a fluid         tight seal between the inner wall of the casing tubular 4 and         the lower tubular 6″, and     -   lever screws 23 having one end fixed with their screw head         situated underneath the flange 11 and the other end arranged         underneath the inner tubular flange 56.

As for the first embodiment the top components comprising the top drive part 2, the upper cam body 18, the upper impact piece 20, the lock ring 21 and the upper gear teeth 42 form the assembly called the top cover 100. Further, the mid components comprising lower cam body 16, the lower gear teeth 40, the mid sleeve 51, the releasable wheels 52, the triangular brackets 53, the lower sleeve 54, the elongated brackets 55, the inner tubular flange 56 and the lower sleeve springs 56 form the assembly called the force transferring means 200.

Initially the tool 1 is lowered into the casing tubular 4,5 until its threaded part 5 abuts the lower impact piece 10. In this starting position the abutting impact piece 10 prevents any downward axial displacement of the inner tubular 6 since the impact piece 10 is coupled to the inner tubular 6 by the screws 57 and also to the lower cam body by the locked wheels 52. Exertion of axial forces on the tool 1 in direction of the casing tubular 4,5 cause corresponding axial displacements of the top drive part 2, the upper impact piece 20 and upper cam body 18. In absence of any rotation the upper cam body 18 will impact the lower cam body 16 in an impact area 32, causing an axial force to be exerted also on the latter 16. The force will release the wheel 52 which again causes the lower end of the lower cam body to impart downward directed pressure on the inner tubular flange 56. Further, the inner tubular flange 56 abuts the lower sleeve 54, creating the axial pressure on the flange 11 and thus the zigzag pattern induced radial displacement of the dies 34. The flange springs 25 and the lower sleeve springs 56 arranged between the flange 11 and the lower impact piece 10 and between the flange 11 and the lower sleeve 54, respectively, ensure re-positioning of the sleeve 8 and the flange 11 when the dies 34 are released from the inner tubular 6 (see below).

In absence of any rotation the upper cam body 18 and the top drive part 2 may in this pre-tensioning situation be lifted up until impact occurs between the upper cam body 18 and the upper impact piece 20. Exertion of any further upwards directed force would thus be transferred to the lower tubular 6, causing a larger axial force and thus an additional clamping force onto the inner walls of the casing tubular 4 from the dies 34 in the same way as for the first embodiment.

Note that both the initial pre-tensioning clamping and the additional clamping are performed without any rotational movements of the tool 1.

Release of the tool 1 from the casing tubular 4 may be achieved by lowering the top drive part 2 and the upper cam body 18 applying a downward directed force, and subsequently enforcing a counterclockwise (or alternatively clockwise) rotation. The latter rotation forms an interconnection between the upper cam body 18 and the lower cam body 16 in contrast to simple impact 32 in absence of rotation. During rotation upper cams 33 with upward directed inclined planes 37 at the lower part of the upper cam body 18 are meshing with corresponding inclined planes 37′ on the upper part of the lower cam body 16, thereby lifting the latter axially upwards (see FIG. 4). Due to the axial displacement of the now interconnected bodies 16,18 and the locking of the wheels 52 inside their respective recesses on the lower cam body 16, the component constituting the force transferring means 200 releases the pressure on the flange 11 causing a further spring induced 25,58 release of the dies 34 from the casing tubular 4,5. Upper gear teeth 42 may be arranged between the top drive part 2 and the upper cam body 18 that are configured to mesh with the top drive part 2 when impact 30 exists (or about to take place) between the upper cam body 18 and the upper impact piece 20 (see FIG. 5), i.e. when the top drive part 2 is in its upper position. Further, arrangement of the first cam springs 26 ensure that such an impact 30 prevails in the absence of downward directed axial force (F).

The second cam springs 17 ensure positioning of the top drive part 2 relative to the lower cam body 16.

To be able to release the tool 1 manually, e.g. in case of any loss of rotational freedom between the two cam bodies 16,18, the tool 1 may be arranged with dedicated release screws 23 fastened underneath the flange 11, going through dedicated holes in the lower sleeve 54. By inserting suitable tools into aligned passages 60 into the lower impact access is gained to the release screws 23. A Clockwise directed turns of these screws 23 cause the screw ends to abut underneath the inner tubular flange 56, which again causes an upwards movement of the component constituting the force transferring means 200 and the inner tubing 6. The further mechanisms are identical to the regular release described above.

In the preceding description, various aspects of the apparatus according to the invention have been described with reference to the illustrative embodiment. For purposes of explanation, specific numbers, systems and configurations were set forth in order to provide a thorough understanding of the apparatus and its workings. However, this description is not intended to be construed in a limiting sense. Various modifications and variations of the illustrative embodiment, as well as other embodiments of the apparatus, which are apparent to persons skilled in the art to which the disclosed subject matter pertains, are deemed to lie within the scope of the present invention. 

1. A casing tool (1) for connecting casing tubulars (4,5) using a top drive, the casing tool (1) comprising a top cover (100) connectable to the top drive and an elongated inner body (6) connected releasingly to the top cover (100), said inner body (6) comprising a first longitudinal part (6′) slideably arranged within the top cover (100) and a second longitudinal part (6″) guidable into a casing tubular (4,5), characterized in that the casing tool (1) further comprising a first sleeve (8,11) arranged concentric and axial displaceable along at least part of the inner body (6) at an axial distance (d) from the top cover (100), force transferring means (200) for transferring axially a first external axial force (F1) exerted on the top cover (100) at least partly to the first sleeve (8,11), at least one clamp (34) connected radially displaceable to the first sleeve (8,11) for engaging the inside wall of the casing tubular (4,5) and radial displacement means (9) extending at least partly along the second longitudinal part (6″) of the inner body (6) for imparting radial displacement on at least one of the at least one clamp (34) during relative axial displacement of the first sleeve (8,11) and the inner body (6).
 2. The casing tool (1) in accordance with claim 1, characterized in that the first external axial force (F1) being exerted after an obstruction of axial displacement of the inner body (6) relative to the casing tubular (4) during use.
 3. The casing tool (1) in accordance with claim 1 or 2, characterized in that the casing tool (1) further comprising a first impact means (10) configured to abut the end of the casing tubing (4,5) during insertion therein, where an obstruction of the axial displacement of the inner body (6) relative to the casing tubular (4) during use is ensured by connecting the first impact means (10) to the inner body (6) via the force transferring means (200).
 4. The casing tool (1) in accordance with claim 3, characterized in that the first impact means (10) comprising a first impact face (10′) situated between the end of the first sleeve (8,11) facing the top cover (100) and the radial displacement means (9).
 5. The casing tool (1) in accordance with one of the preceding claims, characterized in that the force transferring means (200) comprising a second sleeve (14-17;16,51) adjacent to the end of the top cover (100) facing the second longitudinal part (6″) and at least one locking means (12;52-58) arranged in contact with the axial end of the first sleeve (8,11) facing the top cover (100), wherein the force transferring means (200) is configured to activate a mainly casing tubing directed axial displacement of the at least one locking means (12;52-58) when an axial force is exerted on the second sleeve (14-17;16,51).
 6. The casing tool (1) in accordance with one of the preceding claims, characterized in that the first sleeve (8,11) comprising an inner tubing (8) extending at least across the radial displacement means (9′) situated on the inner body (6) and a flange (11) connected to the end of the inner tubing (8) facing the top cover (100), the outer diameter of the flange (11) being larger than the outer diameter of the inner tubing (8).
 7. The casing tool (1) in accordance with one of the preceding claims, characterized in that the radial displacement means (9) comprising at least one first tapered face (9′).
 8. Casing tool (1) in accordance with claim 7, characterized in that the at least one of the at least one clamp (34) comprising at least one second tapered face (9″) facing the at least one first tapered face (9′).
 9. Casing tool (1) in accordance with one of the preceding claims, characterized in that the axial end (18) of the top cover (100) facing the second longitudinal part (6″) and the axial end of the force transferring means (200) facing the top cover (100) are configured as interacting cam bodies (18,16′) allowing interconnection by rotation.
 10. Casing tool (1) in accordance with claim 9, characterized in that the interacting cam bodies (18,16′) are configured to allow a top cover directed axial displacement of the second sleeve (14-17;16,51) when the interacting cam bodies (18,16′) are rotated into the interconnected state and a third external axial force (F3) is exerted on the top cover (100), wherein said axial displacement of the second sleeve (14-17;16,51) causes the at least one clamp (34) to release the radial force on the casing tubular (4,5) set up by any radial displacement.
 11. Casing tool (1) in accordance with one of claims 5-10, characterized in that the casing tool (1) further comprising at least one second sleeve connected release mechanism (23,31,34,35;23,60) configured to allow a top cover directed axial displacement of the second sleeve (14-17;16,51).
 12. Method using a casing tool (1) in accordance with one of claims 1-11, the method comprising the following steps: inserting the second longitudinal part (6″) of the inner body (6) a predetermined length into the casing tubular (4,5), the length being set by a first impact means (10) connected to the inner body (6) to hinder axial displacement of the inner body (6) relative to the casing tubular (4,5) and exerting a first casing tubular directed external axial force (F1) on the top cover (100) causing equally directed axial displacements of the top cover (100), the first sleeve (8,11) and the at least one clamp (34), whereby engagement of the casing tool (1) with the casing tubular (4,5) is achieved by interaction with the radial displacement means (9) imparting radial displacement of at least one of the at least one clamp (34) during said axial displacements.
 13. Method in accordance with claim 12, characterized in that the method further comprising the step: releasing the first casing tubular directed external axial force (F1) on the top cover (100), exerting a second external axial force (F2) directed opposite to the first external axial force (F1), thereby exerting a second external axial force directed tension on the inner body (6) increasing the relative axial force between the clamp (34) and the inner body (6).
 14. Method in accordance with claim 12 or 13, characterized in that the method further comprising the step: exerting a third external axial force (F3) on the top cover (100) in direction of the casing tubular (4,5) causing equally directed axial displacements of top cover (100) and rotating the top cover (100), thereby achieving an interconnected assembly comprising the top cover (100), the second sleeve (14-17;16,51) and the inner body (6) and raising the assembly, causing a top cover directed axial displacement of the first sleeve (8,11) and the at least one clamp (34), thereby releasing the engagement between the casing tool (1) and the casing tubular (4,5) through interaction with the radial displacement means (9).
 15. Method in accordance with one of claims 12-14, characterized in that the method further comprising the step: activating at least one second sleeve connected release mechanism (23,31,34,35;23,60) causing a top cover directed axial displacement of the first sleeve (8,11) and at least one of the at least one clamp (34), thereby releasing the engagement between the casing tool (1) and the casing tubular (4,5) through interaction with the radial displacement means (9). 